Inertia switch for deceleration signaling system

ABSTRACT

An inertia switch assembly of the type adapted for use in a signaling system for motor vehicles. The assembly includes a pair of normally open contacts disposed in circuit with an electrically actuated device comprising an element of said system, and means for closing said contacts upon the sensing of the deceleration of the motor vehicle at a predetermined rate.

United States Patent [72] I Inventor Lynn E. Ellison 44 Industrial Road,Crystal Lake, Ill. 60014 [21] Appl. No. 7,439 [22] Filed Jan. 12,1970

Division of Ser. No. $71,856, Aug. 11,1966, 3,501,742.

Patented Aug. 24, I971 [5 4] INERTIA SWITCH FOR DECELERA'I'ION SIGNALINGSYSTEM 5 Claims, 7 Drawing Figs.

[52] US. Cl 200/6l.48, 3 35/255 [51] Int. Cl ..II01h 35/14 50] Field ofSearch 200/61.45-6l.53;

[ 5 6] References Cited UNITED STATES PATENTS 2,986,615 5/1961 HardwayZOO/61.45 M 1,138,808 5/1915 Tatum 335/255 X 2,751,575 6/1956 Jacobs etal. 340/262 X 3,278,766 10/1966 Ticknor ZOO/61.45 X

Primary Examiner Robert K. Schaefer Assistant Examiner-M. GinsburgAttorney-Olson, Trexler, Wolters & Bushnell ABSTRACT: An inertia switchassembly of the type adapted for use in a signaling system for motorvehicles. The assembly includes a pair of normally open contactsdisposed in circuit with an electrically actuated device comprising anelement of said system, and means for closing said contacts upon thesensing of the deceleration of the motor vehicle at a predeterminedrate.

INERTIA SWITCH FOR DECELERATION SIGNALING SYSTEM REFERENCE TO RELATEDAPPLICATION This application is a division of US. application Ser. No.571,856, filed Aug. ll, 1966, which application matured into U.S. Pat.No. 3,501,742 on Mar. 17, 1970.

This invention relates generally to an automotive signal system and moreparticularly to an automatic signal system for warning followingvehicles of unexpected changes in motion of a vehicle. a

Large numbers of automobiles commonly follow closely behind each otherat .high rates of speed on todays modern highways and expressways. Ifone of the automobiles decelerates, stops or backs up in an unexpectedmanner, the following cars often collide in a series of rear end chaincollisions. These chain collisions result from the failure of drivers ofthe following cars to anticipate the deceleration, stopping or backingup of an automobile several cars ahead in the line. By the time a carimmediately ahead of a following automobile begins to d'ecelerate, thedriver of a following car has insufficient time in which to react andstop his vehicle. The result is a series of rear end collisions of alarge number of cars involving extensive personal injuries and propertydamage.

The most common prior art solution to this problem is the use of brakelights on the rear of automobiles. The brake lights warn a followingdriver that the car immediately ahead is slowing down or stopping.However, the brake lights on cars further ahead are obscured by the carimmediately ahead and do not give a follower driver warning of animpeding slowdown or stoppage of the line of cars. Also, the brakelights are energized by even the slightest pressure on a brake pedal.This results in an oversignalling which lessens the effectiveness of thebrake lights as a warning of rapid deceleration. The effectiveness ofthe common brake light is still further reduced because the light variesgreatly in location on the vehicle, in size and is often used as a taillight as well as a brake light.

In addition to the common brake light, there are many prior art devicesfor indicating vehicle turns, vacuum conditions at a carburetor, thesesignal systems all include complex switching systems which oversignaland provide many meaningless and unimportant signals. The numerousandvaried signals reduce the effectiveness and reliability of thesignalling system, since they are confusing and tend to be ignored. Inaddition, the prior art signalling systems lack the necessaryversatility to warn of a vehicle's deceleration and to provideselectively actuatable signal forindicating that a vehicle is stopped orbacking up.

Therefore, it is an object of this invention to provide an improvedsignalling system which is readily visible for warning ears severalpositions behind a vehicle that the vehicle is decelerating at arelatively high rate, is stopped, or is backing up. I

Another object of this invention is to provide a simple, easilyunderstood signalling system which is actuated by deceleration in excessof a predetermined rate to warn following vehicles of a rapiddeceleration to give drivers of the following vehicles sufficient timein which to stop.

Another object of this invention is to provide a signalling system usinga rugged, economical inertia switch for indicating deceleration inexcess of a given rate caused by switching due to curves or rough roads.

Another object of this invention is to provide an automatic warningsignal which is actuated by only high rates of decelearation tending tocause accidents and is unaffected by normal or routine levels ofdeceleration, signalling of which would tend to cause disregard of thesignal by following drivers.

Another object of this invention is to provide a signalling system foruse by a vehicle operator when stopped along a highway and when enteringheavy or high speed traffic.

Another object of this invention is to provide an automatic warningsignal to indicate when a vehicle is backing up.

These and other objects and features of the invention will become moreapparent upon a reading of the following detailed description, taken inconnection withthe accompanying drawings, wherein:

FIG. 1 is a view, as seen from a following vehicle, of a series ofvehicles in a line of traffic with a signal unit, forming a preferredembodiment of the invention, mountedin the rear of the vehicles ahead ofthe following vehicle;

FIG. 2 is an enlarged view of the signalling unit of FIG. 1;

FIG. 3 is an enlarged view, taken along the line 33 of FIG. 2,illustrating the relationship of a component-mounting partition and lensassembly to a housing for the signal unit;

FIG. 4 is an enlarged view, taken along the line 44 of FIG. 2, furtherillustrating the relationship of the componentmounting partition, thelens assembly and the components of the signal unit;

FIG. 5 is an enlarged perspective view of a pendulum-type inertia switchused in the signal unit of FIG. 2; 7

P16. 6 is an enlarged elevational view of the switch of FIG. 5; and

FIG. 7 is a schematic drawing illustrating a control circuit used withthe signal unit of FIG. 2. I

Referring now to the drawings in greater detail, there is shown in FIG.1 a view of aline or chain of preceding vehicles 10 as seen by thedriver of a following vehicle in the line. It should be noted that thebrake and tail lights 12 of only the immediately preceding vehicle 10are visible to the driver of the following vehicle. Brake lights on thevehicles ahead of the immediately preceding vehicle are obscured by thebulk of the immediately preceding vehicle and are not visible to thedriver of a following vehicle. However the driver of a following vehiclecanlook through rear windows 14 and Windshields 16 of 7 severalpreceding vehicles in the chain and see a signal unit 20 mounted on arear window. shelf 22 of the preceding vehicle 10, Since the signalunits 20 of the preceding vehicles are positioned in the direct line ofvision of a following driver and are mounted in the transparent windowarea of the vehicle, the signal unit for a vehicle severalpositionsahead of a following driver is clearly visible.

Referring now to FIG. 2, the signal unit 20 is mounted on the rear shelf22 of a vehicle by a pair of mounting assemblies 24. The mountingassemblies 24 include a threaded conduit or tube 26 which is mountedwith a threaded nut or head portion 28 in downwardly protruding arcuaterecess or dish 30. The

dish 30 is integrally formed with a generally rectangular hous-' ing orcasing- 32. A spacer 34 is mounted intermediate the dish 30 and shelf 22to position the housing 32 a predetermined distance above the shelf 22.A suitable nut-and-washer combination 36 is connected to the conduit 26beneath the shelf to securely connect the signal unit 20 to the shelf.The arcuate dish 30 permits the conduit 26 to be angled relative to avertical axis of the signal unit 20 to facilitate mounting the housing32 on shelves of different arcuate curvatures. The mounting assembly 24is adapted for use with either concave or convexly curved shelves 22,since the conduit 26 can be pivoted outwardly or inwardly relative tothe casing 32.

The casing 32 includes a generally U-shaped channel or body member 44which is closed at opposite ends by a pair of caps or end walls 46 and48. A plurality of lenses 50 are mounted at the mouth of the generallyU-shaped channel or body 44. The lens 50 includes an amber lens 52 forsignalling left turns of a vehicle, an amber lens 54 for signallingright turns of a vehicle, and a red central lens 56 for signallingbraking lenses 52, 54 and 56 are shaded by an outwardly extending visorsection 60 (see FIGS. 2 and 3) of the generally U-shaped body or channel44.

As is best seen in generally U-shaped body or channel 44 includes alongitudinally extending upper sidewall 64 which is located in aspaced-apart generally parallel relationship with a longitudinallyextending base or sidewall 66 of the body member 44. The sidewalls 64and 66 are interconnected by a rear wall 68 which extends generallyperpendicularly to the two sidewalls. A first set of longitudinallyextending mounting slots 70 and 72 are integrally formedwith thesidewalls 64 and 66 for supporting a mounting panel or partition 74 onwhich components of the signal unit are mounted. A second set oflongitudinally extending mounting slots 76 and 78 are integrally formedwith the sidewalls 64 and 66 in a spaced-apart substantially parallelrelationship with the mounting slots 70 and 72 for retaining atransversely extending panel or partition 80. A pair of longitudinallyextending lens mounting slots 82 and 84 are integrally formed withthesidewalls 64 and 66 for mounting the lenses 52, 54, 56 in thegenerally U-shaped body 44. The generally U-shaped body member 44 andthe mounting slots are advantageously formed of an integral aluminumextrusion.

The longitudinally extending mounting partition 74 with electricalcomponents mounted and wired thereon, and the transversely extendingpartition 80 are mounted in the body 44 by sliding them longitudinallyrelative to the body in the slots 70, 72, 76 and 78. Once the mountingpartition 74 is positioned in the body 44, the lenses 52, 54 and 56 areslid longitudinally into the slots 82 and 84 to mount them in the body44. After the partition 74 andlenses 50 have been positioned in the body44, the end walls 46 and 48 are slid over opposite ends of the body 44to provide an enclosed casing for the components which are mounted onthe partition 74.

As is best seen in FIG. 4, the generally U-shaped body 44 is dividedinto a plurality of sections or compartments 90, 92, and 96 by thelongitudinal mounting partition 74, the transverse partition 80, and asecond transverse partition 98 which extends parallel to the firsttransverse partition 80 in an abutting relationship with the lenses 52and 56. A light source or bulb 100 is mounted on the partition 74 in thecompartment 90 to indicate when a vehicle is going to make a lefthandturn by radiating light rays through the amber-colored lens 52.Similarly, a light source or bulb 102 is mounted in the compartment 94to indicate when a vehicle is going to make a right-hand turn byradiating light rays through the amber colored lens 54. A pair ofdual-filament bulbs or light sources 104 and 106 are mounted in aspaced-apart relationship on mounting slots 82 and 84 in front of theassociated light sources. Once the mounting partition 74 and lenses havebeen positioned in the body 44, the caps or end walls 46 and 48 arepressed into frictional engagement with the end of the generallyU-shaped body 44 to seal the signal unit 20. The signal unit isthenready for mounting, on the assemblies 24, in the rear of a vehiclewith the lenses 52, 54 and 56 facing rear wardly, as indicated in FIG.1, relative to the vehicle.

The inertia switch 116 is shown in greater detail in FIGS. 5 and 6. Theinertia switch includes a baseplate 130 which is mounted against thelongitudinally extending partition 74 (see FIGS. 3 and 4) to positionthe inertia switch with a mounting frame 132 extending outwardly fromthe baseplate 130. The mounting frame 132 extends rearwardly relative toa vehicle in which the signal unit 20is mounted. A pendulum assembly 134is pivotably mounted by a pin 136 on upstanding flanges 138 which areformed integrally with opposite sides of the frame 132. The pendulumassembly 134 includes an armature plate or frame on which a mass orweight 142 is secured. The pendulum assembly .134 is connected to thepivot pin 136 by means of a pair of spaced-apart inwardly extending earsor tabs 144 which .engage outer surfaces of the upstanding flanges 138.

A movable reed-type contact assembly 148 is mounted on the armatureplate 140 for pivotal movement relative to a fixed-contact assembly 150mounted on a post 152 supported by the baseplate 130. The movablecontact assembly 148 includes a reed or lever 156 which is connected bya suitable tegrally formed with the arm 160 for biasing the spring leveror reed 156 relative to the armature plate 140. The adjusting tang 162,can be bent to vary the spacing between the fixed contact 150 and anelectrical contact 164 on the spring lever As is perhaps best seen inFIG. 6, the pivot pin 136 is mounted in substantial alignment with thearmature plate 140 the partition 74 in the compartment or section 92.The dualfilament bulbs 104 and 106 indicate when a brake system for avehicle is being energized and when the vehicle is decelerating inexcess of a predetermined rate. The bulbs 104 and 106 signal theenergization of the vehicle-braking system by emitting a relatively weaklight of approximately 6 can- -dlepower from filaments 108 and 110.

As will be explained in greater detail subsequently, the bulbs 104 and106 indicate a deceleration of a vehicle in excess of a predeterminedrate of deceleration by emitting bright flashing light of approximately60 candlepower from the filaments 112 and 114. In addition, an inertiaswitch 116 and a Iasher unit 118 are mounted on the panel 74 in thecompartment 92. A relatively narrow longitudinally extending wiringcompartment 96 is provided between the rear of the panel 74 and the rearwall 60 of the generally U-shaped body 44. The light sources 100 and102, 104 and 106, the flasher 118 and the inertia switch 116 areinterconnected by wiring, connected in'accordance with the schematicdiagram of FIG. 7, which has been omitted for purposes of clarity fromFIG. 4. It will be understood, of course, that the components which aremounted on the partition 74 have terminals which extend through thepartition to facilitate interconnecting the components which are wiredbefore the partition is slid into the housing 32.

In view of the foregoing remarks, it will be apparent that the signalunit 20 is a compact readily assembled structure. The assembly of theunit is facilitated by the utilization of a generally U-shaped body 44having integrally formed mountto cause the pendulum assembly 134 to tendto swing to'the left, as seen in FIG. 6. This leftward movement resultsfrom a center of gravity .168 of the pendulum assembly 134 tending topivot the pendulum assembly around the pivot pin 136 to align the centerof gravity 168 with a vertical axis or centerline 170 extending throughthe pivot pin 136. When the pendulum assembly 134 is in its normalunrestrained position, the vertical axis 170 forms a centerline for thependulum assembly and extends through the center'of gravity 168 and thepivot pin 138. However, the center of gravity 168 of the pendulumassembly 134 is biased an arcuate distance of 2 to the right of thecenterline 170 by a generally U-shaped stop member or lever arm 174.Therefore, when the inertia switch 116 is in the normal or unactuatedposition shown in FIGS. 5 and 6, the armature plate of the pendulumassembly 134 presses outwardly against the stop arm 174 which retainsthe center of gravity 168 of the pendulum assembly an arcuate distanceof 2 inwardly toward the baseplate 130 from its normal positioncoincident with the centerline 170 of the pendulum assembly.

When a vehicle in which the signal unit 20 is installed decelerates at arelatively high rate, the pendulum assembly 134 swings around the pivotpin 136 forwardly toward the front of the car, or inwardly toward thebaseplate 130, due to inertia forces acting on the mass or weight 142.This pivoting movement results in the contact 164 making an electricalconnection with the fixed contact 150, as illustrated in dashed lines inFIG. 6. The arcuate distance through which the pendulum assembly 134pivots in order to make an electrical connection between the fixedcontact and the movable contact 164 is approximately 9". However, due tothe 2 bias applied to the pendulum assembly 134, the inertia forces towhich the pendulum assembly must be subjected to move the pendulumassembly inwardly to engage two contacts 150 and 164 is equal to theinertia forces required to pivot the pendulum assembly through anarcuate distance of 1 1 or 1.12 GS of deceleration. The initial twodegree bias on the pendulum assembly 134 by the stop arm 174 preventsthe pendulum assembly from oscillating due to rough roads and makingfalse or spurious engagement between the fixed contact 150 and movablecontact 164. When the two contacts 150 and 164 are in engagement thelight sources 104 and 106 for indicating deceleration of the vehicle areenergized. Of course, the pendulum-type inertia switch 116 can beadjusted, by a suitable positioning of the contacts 150 and 164, and thestop arm 174, to be actuated by any desired rate of deceleration.

The magnetic assembly 178 includes a coil 180 and a core While thebrake'circuit for the vehicle is energized, the coil 180 is energized toretain the fixed contact 150 in engagement with .the movable contact 164of the pendulum assembly 134. If the initial deceleration of the vehicleexceeds 1.1 2 GS,the signal lights 104 and 106 are energized and thecontact 164 locked in engagement with the contact 150 by the coil 180.If the rate of deceleration falls below 1.12 GS, the signallights 104and 106 are maintained in an energized state by the holdpiece 182. Thestop arm 174 is mounted on the coil 180 at an outermost end of the corepiece 182. The coil 180 is connected to wiring terminals 184 and 186which are wired to a main control circuit for the signal unit. Whenenergized, the outwardly extending magnetic assembly 178 retains thearmature plate 140 in an inward position, indicated by dashed lines inFIG. 6, to maintain the fixed contact 150 and movable contact 164 inengagement. Since the frame piece 132 is made of a soft iron and,includes a leg section 190 extending between the baseplate 130 and thecoil 180, the frame 130 provides a magnetic path-for flux originatingfrom the coil 180. Thus, when the coil 180 is energized, flux flows fromthe coil through the leg 190 of 'the frame member 132, the flanges 138,cars 144 to the plate 140 and the core piece 182. The flow of flux isfacilitated by the angular head section 194 of the armature plate 140which contacts the outwardly extending frame 132 when the pendulumassembly 134 is pivoted inwardly due to a deceleration of a vehicle inexcess of 1.12 GS or an energization of the coil 180.

A schematic drawing is set forth in FIG. 7 illustrating a main controlcircuit for the signal unit 20. The main control circuit includes theturn signal lights 100 and 102 for indicating the direction in which avehicle is going to turn. The turn signal lights 100 and 102 areconnected to a front-turn signal-light circuit for the vehicle by leads200 and 202, so that the turn signal lights are not energized by anactuation of a braking system for the vehicle. The double-filamentedfilamented light sources 104 and 106 have filaments 108 and 110 forindicating a braking of the vehicle and the filaments 112 and 114 forsignaling a deceleration of the vehicle. As previously explained, aboutten times as much light is emitted from the filaments 112 and 114 tosignal a deceleration of a vehicle as is emitted from the filaments 108and 110 to signal a braking of the vehicle. The filaments 108 and 110are interconnected in' series by a lead 204 which is connected to thebrake circuit for the vehicle by a lead 206. The two filaments 112 and114 for signalling a deceleration of the vehicle are interconnected by alead 208 which is connected to the interrupter or flasher unit 118byalead 210.

The inertia switch assembly 116 is connected to the brake circuit forthe vehicle through a lead 212 which is connected to the movable contact164 by the armature plate 140. When the deceleration ofthe vehicle is inexcess of 1.12 GS, the pendulum assembly 134 is swung away from the stop174 to make an electrical connection between the movable contact 164 andfixed contact 150. if this deceleration is due to an application of thebraking system for the vehicle, current flows from the energized brakecircuit through the leads 206 and 212 through the contacts 164 and 150to energize the coil 180 which locks the contacts 150 and 164 inengagement. in addition, current flows through the lead 206 from thebrake circuit and the contacts 164 and 150 to a lead 216 which isconnected to the flasher unit 118. The flasher unit 118 is normallyclosed so that current initially flows through the flasher unit and thelead 210 to energize the filaments 112 and 114 of the decelerationsignal lights 104 and 106. As current flows through the flasher unit118, the flasher is heated up to interrupt the circuit at a rate of 90to 120 c.p.s. Thus, the filaments 112 and 114 emit a bright flashingsignal which is clearly visible, even through the rear windows andWindshields of several preceding cars, to warn a driver of a followingcar of the relatively rapid deceleration of a preceding vehicle.

ing action of the coil 180 until the brake circuit for the vehicle isdeenergized. However, if the initial deceleration of the vehicle doesnot exceed 1.12 GS, that is, the vehicle merely decelerates at arelatively slow rate, the filaments l 12 and 114 are not energized toemit a bright flashing signal. However, the low intensity'filaments 108and 112 are energized by the slow deceleration, through the leads 206and 204 from the brake circuit, to warn following drivers that thebrakes of the vehicle have been applied. Therefore, the signal unitavoids unnecessary signalling by emitting a bright flashing signal onlywhen a vehicle is decelerating at a relatively high dangerous rate.

In addition to the aforementioned main .signalling circuit, auxiliarycircuitry 218 is included with the signal unit 20. The auxiliarycircuitry 218 includes a manually actuated dashboard-mounted emergencyswitch 220 which is connected to an ignition circuit for the vehicle bya lead 222. The selectively actuatable manual switch 220 is alsoconnected by the leads 224 and 226 to the flasher unit 118, which is inturn connected by the leads 210 and 208 to the filaments 112 and 114 ofthe signal lights 104 and 106. Therefore, when the ignition circuit forthe vehicle is energized and the switch 220 is closed, the signal lights104 and 106 are energized to emit a bright flashing signal to warnapproaching drivers of the vehicle. It is anticipated that the manuallyactuatable switch 220 will be closed to emit a signal when the vehicleis pulled off to the side of the road, due to mechanical failure orother reasons, and when the vehicle is entering relatively fast-movingtraffic from a side entrance. Of course, there are many other emergencysituations in which the manually actuatable switch 220 canadvantageously be closed to emit a bright flashing signal from thelights 104 and 106.

in addition to the manually actuatable switch 220, a reverse gear switch228 is provided in the auxiliary circuit 218. The reverse gear switch228 is closed when the gear selector for the vehicle is shifted into areverse position. The switch 228 is connected to an ignition circuit forthe vehicle by a lead 230 and is connected to the flasher 118 and signallights 104 and 106 by the leads 226 and 232. A diode 234 is connected tothe switch 228 to prevent current from flowing through the lead 206 fromthe vehicle brake circuit, the lead 212, the contacts 164 and 150, andthe leads 216 and 226 to the ignition circuit when the brakes for thevehicle are applied while the gear selector is in a reverse gearposition to close the switch 228.

The manually actuatable switch 220 and reverse gear switch 228 are bothconnected to the coil 180 by the lead 216. Therefore, when either theswitch 220 or 228 is closed, the coil 180 is energized to magnetize thecore piece 182. The magnetizedcore piece 182 normally tends to attractthe plate of the pendulum assembly 134 to pivot the pendulum assembly134 inwardly to the position indicated in dashed lines in FIG. 6.However, the pendulum assembly is initially in engagement with the stoparm 174 which is mounted on the outermost end of the core piece 182.Therefore, the stop arm 174 is magnetized and attracts the plate 140 toretain the pendulum assembly in the position indicated in solid lines inFIG. 6. The stop arm 174 effectively short circuits the magnetism of thecore piece 182 to prevent the core piece from attracting the plate 140and swinging the pendulum inwardly to close the contact 150. Since thecontacts 150, 164 are not closed when the manual switch 220 or thereverse gear switch 228 is operated, current cannot be conducted fromthe ignition circuit through the lead 226 and 216, the contacts and 164,and the leads 212 and 206 to the brake circuit for the vehicle.Therefore, the brake lights are not energized when either the manualswitch 220 or reverse gear switch 228 is operated.

It should be noted that the stop arm 174, which is formed of a softiron, does not prevent the pendulum assembly 134 from being attracted bythe core piece 182 when the vehicle decelerates at a rate in excess ofl.l2 GS. This is because the core piece 182 is not normally magnetizeduntil the contacts 150 and 164 are closed, due to the inward movement ofthe pendulum assembly 134. Since the core piece 182 is not magnetizeduntil after the plate 140 has moved out of engagement with the stop arm174, the stop arm 174 does not effectively short circuit the magneticfield from the core piece 182 to prevent the pendulum assembly 134 fromswinging inwardly during the normal operation of the inertia switch 116.IN view of the preceding remarks, it will be apparent that the stop arm174 retains the pendulum assembly in a spaced-apart relationshiprelative to the core piece 182 when the coil 180 is energized before thependulum assembly swings inwardly out of engagement with the stop arm174. The switch contacts 150 and 164 remain open and current isprevented from flowing from the auxiliary circuitry 218 to the brakecircuit for the vehicle to give a false braking signal. Of course, thestop arm 174 could be replaced with a stop arm of brass or othernonmagnetizable material rather than a soft iron. However, if this wasdone, a diode would have to be placed in the main circuit lead 212 toprevent current from flowing through the contacts 150 and 164 to thelead 206 to the brake circuit for the vehicle. The diode would also benecessary to prevent the filaments 108 and 110 of the signal lights 104and 106 from being energized.

The operation of the signal unit will be apparent from the foregoingdescription However, for purposes of affording a more completeunderstanding of the invention, a functional description is now providedof the mode in which the component parts cooperate. The signal unit 20is mounted in the rear of a vehicle with a plurality of signal lights100, 102, 104 and 106 for warning following drivers of changes in motionof the vehicle. The signal lights 100 and 102 will warn the followingdriver that the vehicle is going to turn. The signal lights 104 and 106will warn following drivers, with a low intensity signal from thefilaments 108 and 110, that thebrakes for the vehicle have been applied.if the vehicle should decelerate at a rate in excess of 1.12 G8, theinertia switch 116 will be closed to energize the filaments 112 and 114of the signal lights 104 and 106 to emit a bright flashing signal towarn following drivers of the comparatively abrupt change in motion ofthe vehicle. Of course, individuals skilled in the art can adjust theswitch 116 to signal any desired rate of deceleration other than'theexemplary value of 1.12 GS.

It should be noted that the signal unit 20 emits only three easilyunderstood signals which indicate the basic changes in .notion of thevehicle'which need to be called to the attention of the followingdrivers. Thus, a turning of the vehicle is indicated by a signal throughthe amber lenses 52 and 54 from the light sources 100 and 102. A brakingsignal indicated by a low intensity light is emitted from the filaments108 and 110 of the light sources 106 and 104 through the red lens 56. Inaddition to these two easily understood signals, a bright flashingsignal is emitted from the filaments 112 and 114 of the light sources104 and 106 when the deceleration of the vehicle exceeds a predeterminedamount (i.e., 1.12 GS) to actuate the inertia switch 116.

The relatively simple, rugged inertia switch 116 will not emit spurious,confusing signals due to rough roads or curves because the pendulumassembly 134 is retained in a 2 biased position pressing against thestop member 174 until the vehicle starts to decelerate at a relativelyhigh rate. Once a vehicle has started to decelerate at a rate in excessof 1.12 GS, the coil 180 is retained in an energized state as long asthe brake circuit for the vehicle is energized. The energized coil 180locks the contacts 150 and 164 closed to provide a continuous flushingsignal from the light sources 104 and 106. Of course, when the brakesfor the vehicle are released, the brake circuit is deenergized and thecoil 180 is deenergized to enable the pendulum assembly 134 to swing toits normal biased position against the stop member 174.

The signal unit 20 is also activated to emit signals by a closing of theauxiliary switches 220 and 228. The switch 220 is mounted on thedashboard of the vehicle for selective manual actuation to warnfollowing drivers, or drivers approaching a stopped vehicle from therear, of an emergency condition. The

switch 228 is closed by shifting the gear selector to the reverseposition to warn oncoming drivers that the vehicle is backing up.

The assembly of the signal unit 20 is facilitated by the housing orcasing structure 32 which includes a generally U-shaped body member 44into which a mounting panel or partition 74 is slid with the electricalcomponents of the signal unit mounted and wired on the panehln addition,the insertion of the lenses 52, 54 and 56 is facilitated by the mountingslots 82 and 84 which are formed integrally with the body member 44.Once the mounting partition 74, and the electrical components of thesignal unit 20 have been inserted into the casing 32 and the lenses 50installed, the ends of the body member 44 are closed by pressing the capor end walls 46 and 48 into place. The relatively long, narrow signalunit is readily mounted on the rear window shelf of most vehicles, whereit is clearly visible to following drivers, by means of the mountingassemblies 24.

When a vehicle, in which the signal unit 20 is mounted, is being drivendown a turnpike or expressway in heavy traffic, the signal unit 20 willbe visible to the driver of a vehicle several vehicles behind. Thedriver of this following vehicle can look through the clear windows ofthe preceding cars and see the signal unit 20, which is mounted where itis clearly visible, through the Windshields of a number of vehicles. Thedriver of this vehicle will, therefore, be alerted to the impendingdeceleration of the vehicles immediately ahead in time to safely stophis own vehicle. It is the margin of time which the signal unit providesthis driver that will prevent the many .chain collisions which commonlyoccur on expressways.

It is anticipated that the signal unit 20 will find widespread usage onmany types of vehicles and conveyances. For example, the signal unit canadvantageously be mounted on trailers which obscure the signal lights ofa towing vehicle. The signal unit can also be used on motor bikes,camper-trailers, trucks, boats and any similarmoving structure, tosignal a deceleration of the structure. In view of the precedingremarks, it will be apparent that the signal unit 20 can be used with awide range of moving structures. Therefore the .word vehicle, as used inthe claims andspecification, is intended to include any means ofcarrying or transporting something.

It is also contemplated that the inertia switch 116 can be used in anacceleration-signalling unit by merely reversing the orientation of theswitch relative to the vehicle, that is by placing the switch so thatthe frame 132 projects forwardly rather than rearwardly relative to thevehicle. It will be apparent to those skilled in the art that theinertia switch 1 16 can be made from components other than thoseillustrated, such as solidstate devices of known construction. In viewof the many possible changes in structure and uses for the signal unit20, the specific embodiment of the invention herein shown and describedis to be considered as being primarily illustrative. Various changes instructure beyond those described will, no doubt, occur to those skilledin the art; and these changes are to be understood as forming a a partof this invention insofar as they fall within the true spirit and scopeof the appended claims.

1. An inertia switch comprising: a base means; first electrical contactmeans supported by said base means; electromag netic means supported bysaid base means, said electromagnetic means including a core piece and acoil means; a stop means of magnetizable material mounted on said corepiece; a pendulum means supported by said base means and mounted forpivoting movement towards said core piece from a first position inengagement with said stop means to a second position, in response to achange in the rate of motion of said base means, said pendulum meansbeing magnetically retained in said first position by energizing saidcoil means to magnetize said core piece and stop means when saidpendulum means is cally retained inv said second position'by energiiingsaid coil means when said pendulum means is in said second position;

and second electrical contact means connected to said penducuit with anelectrically actuated device, and the operation thereof being effectedby inertial changes of a body upon which. said switch assembly ismounted, said assembly includi ing base means, an inertial elementcomprising means providing apivotal mounting for said pendulum forpivotal movement relative to said base means, a pair of normallyspacedapart contacts adapted to be connected in circuit with saidelectrically actuated device, one said contact carried by said pendulumand the other by said base means, such that inertial v change will causesaid pendulum to pivot from a first position to a second positionwherein said contacts are electrically closed, and selectivelyenergizable electromagnetic means carried by said base means, wherebysaid electromagnetic means when energized attracts and maintains saidpendulum in said second position with said contacts closed regardless of1 the presence of inertial change, and when deenergized permits saidpendulum to move from said second position to said first positionthereby to open said contacts.

3.- A switch assembly as defined in claim 2 further including I stopmeans against which said pendulum 'is engaged when in said firstposition.

4. A switch assembly as defined in claim 2 wherein said pendulumincludes an elongate plate having a mass fixed thereto at an end of saidplate opposite the location of said pivotal mounting, and means engagedagainst said plate to hold said pendulum in the first positiontherebypreventing movement of said pendulum from said first position tothe second position during instances of inertial change less. than apredetermined rate.

5, An inertia switch of the type to be placed in circuit with anelectrically actuated device and operated by inertial changes of a bodyupon which said switch is mounted, said switch including base means, aframe connected to and extending outwardly from said base means,pendulum means carried by said frame for pivotal movement toward saidbase means from a first position to a second position when said bodyundergoes inertial changes exceeding a predetermined rate, biasing meanstending to hold said pendulum means in said first position with thecentral axis of said pendulum means offset a predetermined angulardistance from said base means relative to the vertical axis in order toprevent movement of said pendulum means towards said base means uponinertial changes which are less than said predetermined rate, firstcontact means carried by said base means, second contact means carriedby said pendulum means, said first contact means being spaced apart fromsaid second contact means when the pendulum means is in said firstposition, and said first contact means being in electrical engagementwith said second contact means when said pendulum means is in saidsecond position, and selectively operable magnetic means for attractingand retaining said pendulum means to said second position with saidcontacts in electrical engagement regardless of the rateof inertialchange of said body upon which the switch is mounted.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,601,564 Dated August 24, 1971 Inventor(s) ynn E. Ellison It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Col. 1, line 32, change "follower" to --following-- Col. 1, line 32,change "impeding" to -impending-- Col. 1, line 42, after "carburetor"insert --position of brake and accelerator pedals." and change "these"to -These-- Col. 1, line 63, after "rate" insert "without falsesignalling-- Col. 2, line 65, after "braking" insert --or decelerationof a vehicle. The-- Col. 2, line 68, before "generally" insert --FIG. 3,the-- Col. 3, line 24, after "components" insert --of the signal unit--Col. 3, line 26, after "92" insert "94-- 601. 4, line 19, after "frame"insert "140-- Col. 5, line '59, after "filamented" omit --filamented-Signed and sealed this 16th day of May 1972.

( SEAL Abbeot:

EDWARD ILFLETCIIERJR. ROBERT GOTTSCHALK A ates ting Officer Commissionerof Pa tents ORM PC4050 USCOMM-DC 60376-F'59 l, U 5 GOVERNMENT PFINV'NGOFFICE I '9 0-355-54

1. An inertia switch comprising: a base means; first electrical contactmeans supported by said base means; electromagnetic means supported bysaid base means, said electromagnetic means including a core piece and acoil means; a stop means of magnetizable material mounted on said corepiece; a pendulum means supported by said base means and mounted forpivoting movement towards said core piece from a first position inengagement with said stop means to a second position, in response to achange in the rate of motion of said base means, said pendulum meansbeing magnetically retained in said first position by energizing saidcoil means to magnetize said core piece and stop means when saidpendulum means is in said first position, and said pendulum means beingmagnetically retained in said second position by energizing said coilmeans when said pendulum means is in said second position; and secondelectrical contact means connected to said pendulum means, said firstand second electrical contact means being brought in and out of mutualelecTrical engagement by movements of said pendulum means relative tosaid base means.
 2. An inertia switch assembly of the type to be placedin circuit with an electrically actuated device, and the operationthereof being effected by inertial changes of a body upon which saidswitch assembly is mounted, said assembly including base means, aninertial element comprising means providing a pivotal mounting for saidpendulum for pivotal movement relative to said base means, a pair ofnormally spaced-apart contacts adapted to be connected in circuit withsaid electrically actuated device, one said contact carried by saidpendulum and the other by said base means, such that inertial changewill cause said pendulum to pivot from a first position to a secondposition wherein said contacts are electrically closed, and selectivelyenergizable electromagnetic means carried by said base means, wherebysaid electromagnetic means when energized attracts and maintains saidpendulum in said second position with said contacts closed regardless ofthe presence of inertial change, and when deenergized permits saidpendulum to move from said second position to said first positionthereby to open said contacts.
 3. A switch assembly as defined in claim2 further including stop means against which said pendulum is engagedwhen in said first position.
 4. A switch assembly as defined in claim 2wherein said pendulum includes an elongate plate having a mass fixedthereto at an end of said plate opposite the location of said pivotalmounting, and means engaged against said plate to hold said pendulum inthe first position thereby preventing movement of said pendulum fromsaid first position to the second position during instances of inertialchange less than a predetermined rate.
 5. An inertia switch of the typeto be placed in circuit with an electrically actuated device andoperated by inertial changes of a body upon which said switch ismounted, said switch including base means, a frame connected to andextending outwardly from said base means, pendulum means carried by saidframe for pivotal movement toward said base means from a first positionto a second position when said body undergoes inertial changes exceedinga predetermined rate, biasing means tending to hold said pendulum meansin said first position with the central axis of said pendulum meansoffset a predetermined angular distance from said base means relative tothe vertical axis in order to prevent movement of said pendulum meanstowards said base means upon inertial changes which are less than saidpredetermined rate, first contact means carried by said base means,second contact means carried by said pendulum means, said first contactmeans being spaced apart from said second contact means when thependulum means is in said first position, and said first contact meansbeing in electrical engagement with said second contact means when saidpendulum means is in said second position, and selectively operablemagnetic means for attracting and retaining said pendulum means to saidsecond position with said contacts in electrical engagement regardlessof the rate of inertial change of said body upon which the switch ismounted.